Inhibition of collagenase and melanogenesis by ethanol extracts of <italic>Orostachys japonicus</italic> A. Berger: possible involvement of Erk and Akt signaling pathways in melanoma cells

Orostachys japonicus is an herb that contains several functional components and has traditionally been used to treat various diseases in Asia. In this study, bioactive components from different parts of the O. japonicus plant were investigated, and the contents of the functional components in ethanol extracts of O. japonicus cultivated in Korea and China were compared. The antioxidant effects of O. japonicus ethanol extracts were investigated using Raw 264.7 cells. It was found that 2,2-diphenyl-1-picrylhydrazyl radical-scavenging activity was significantly decreased in the cells treated with the extracts. Moreover, the novel inhibitory functions of O. japonicus extracts on collagenase, elastase, and tyrosinase were established. We also found that O. japonicus extracts strongly inhibited melanin synthesis in B16F10 melanoma cells by decreasing MITF protein levels and activating the Erk and Akt signaling pathways. Thus, these findings would be useful for developing new cosmetic and pharmaceutical formulations based on O. japonicus extracts.